JP2968247B2 - Inspection method of crystal blank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a crystal blank , and more particularly to a method for inspecting a crystal blank for defects on a region- by- region basis.

[0002]

2. Description of the Related Art When a flaw of a crystal blank is inspected by image processing, a read image signal is binarized to emphasize the flaw. A threshold value must be set for the binarization. The threshold value is an important parameter for determining the quality of the inspection result. Conventionally, this threshold value is the same regardless of the location in one crystal blank.

[0003]

In the conventional flaw inspection, 1
Regarding a piece of quartz blank,
The wounds were inspected by applying the same inspection criteria uniformly. However, the crystal blanks to be inspected usually involve variations in the manufacturing process, so that exactly the same crystal blank cannot be produced, and depending on the location of the crystal blank, a loose standard may be acceptable. Therefore, if a flaw is inspected using the same inspection standard, a non-defective product may be determined to be defective, or a defective product may be determined to be non-defective. Further, even if flaw inspection data based on image processing is obtained, there is a problem that data for standardization of inspection and analysis management cannot be obtained effectively because inspection point information is not included. This is not limited to scratches, and has also been a problem when inspecting beveling (chamfering) conditions.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method of inspecting a quartz blank which can effectively determine a scratch on the quartz blank .

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a quartz oscillator.
When inspecting scratches on a quartz blank
The image of the surface must be
Area, the area around the crystal blank excluding the fixed area,
A quartz blank is divided into a plurality of regions of a central region mainly functioning as a moving element, an inspection standard required for the region is set for each of the regions, and each region is inspected according to the set inspection standard. It is an inspection method.

In general, the required inspection accuracy varies depending on the area of the quartz substrate. However, since the conventional method regards the whole as one, the inspection is performed by applying the same inspection standard. Was. In this regard, according to the present invention, the image of the substrate surface of the quartz substrate is divided into a plurality of regions, and the inspection reference required for each region is set for each region. The substrate can be inspected according to different criteria for each region. Therefore, it is possible to truly determine a good product or a defective product. Further, by statistically processing the data obtained from the test results, analysis and analysis can be performed for each region, which is suitable for evaluation.

[0007] When the crystal blank is a strip-shaped blank Te smell, the fixing region of the four corners of the crystal blank co
Corner region, and the peripheral region is the corner region.
The upper and lower sides are parallel to the upper and lower sides of the crystal blank excluding
A pair of band-shaped upper and lower regions and the corner
The left and right sides are parallel to the left and right sides of the crystal blank excluding the area.
A pair of band-shaped left and right regions as sides, and the central region
Is a central region surrounded by the upper and lower regions and the left and right regions.
It is preferable that it is an area . The inspection may be a flaw inspection, a beveling inspection, or a shape inspection.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a schematic configuration diagram showing an embodiment in which the crystal substrate flaw inspection apparatus according to the present invention is applied to a crystal blank for a crystal resonator.

In FIG. 3, reference numeral 1 denotes a mirror-finished strip-shaped crystal blank, usually having a size of 1 × 3 mm to 3 mm.
× 10 mm and a thickness of about 30 μm to 500 μm. The shape of the crystal blank 1 is not limited to a rectangular shape or a rectangular shape, but may be a circular shape having a diameter of about 4 to 8 mm or other shapes.

The crystal blank 1 is mounted horizontally on a mounting table 2. The mounting table 2 is made of sapphire, and a groove is formed in the mounting surface 3 of the mirror-finished mounting table 2 as a concave portion for avoiding sliding and close contact of the crystal blank 1.

A light emitting diode 6 is arranged below the crystal blank 1 so as to surround the crystal blank 1 as shown in FIG. The light from the light emitting diode 6 is vertically shifted from the substrate surface of the quartz blank 1 by 0 ° to −30 °.
At the irradiation angle θ within the range of °, the irradiation is performed from the entire circumferential direction of the side surface of the quartz blank 1 through the mounting table 2. The irradiation angle θ is positive on the front side of the quartz blank 1 and negative on the back side. When a mirror is arranged around the light emitting diode 6, the quartz blank 1 can be uniformly irradiated with light from all directions. The light emitting diode 6 preferably has a high luminance, and a light emitting diode that emits red light to infrared light is preferably used. The reason why the light-emitting diodes 6 of the illuminating means are arranged below the mounting table 2 is to prevent obstacles from coming to the upper side when moving the quartz blank 1 so as to cope with automation of the inspection process and mass production. is there.

On the other hand, the image pickup means 11 is disposed at a position directly above the surface of the quartz crystal blank 1 in a direction perpendicular to the image pickup direction. The imaging means 11 is set so that only the vicinity of the quartz blank 1 is included in the field of view by using, for example, a lens system 12 for imaging light from the CCD camera 13 and the quartz blank 1 on the CCD surface of the CCD camera 13. In this way, light obliquely incident on the crystal blank 1 from the light emitting diode 6 does not directly enter the lens system 12 as it is, and a dark field state is obtained.

An image signal picked up by the CCD camera 13 is input to an image processing device 14. The image processing device 14 includes a feature extraction unit that extracts a feature of a flaw existing in the crystal blank 1 from an input image signal, and a determination unit that determines the presence of a flaw based on the extracted signal. Since the imaging unit 11 puts only the vicinity of the crystal blank in the field of view, the image processing device 14 can perform high-speed image processing of the change in the brightness of the field of view to detect a flaw.

The crystal blank 1 is a vacuum chuck 1
6 and carried into the mounting table 2 by the transfer robot arm 15, and after the flaw inspection, the vacuum chuck 1
6 and is carried out by the transfer robot arm 15.

Now, in the above configuration, the transfer robot arm 15 is attracted to the vacuum chuck 16 and sucked.
The crystal blank 1 transported to the mounting table 2 by
It is mounted on a predetermined position of the mounting table 2. At this time, since a large number of grooves are formed on the mounting surface 3 of the mounting table 2, the quartz blank 1 does not slip on the mounting table 2 and is accurately mounted at a fixed position. Accurate measurement of scratches becomes possible.

When a large number of light emitting diodes 6 arranged below the mounting table 2 emit scattered light toward the quartz blank 1, the scattered light covers the entire side surface of the quartz blank 1. In this case, crystal blank 1
Do not irradiate light from directly above or below. This is because, when irradiated from directly above or below, an image of the quartz blank 1 is reflected on the CCD camera 13 by transmitted light or reflected light. In addition, the base pattern of the mounting table 2 supporting the crystal blank 1 is clearly seen, and it is difficult to determine a scratch (defect) existing in the crystal blank 1.

As shown in FIG. 4, when the crystal blank 1 is irradiated with light from the entire periphery of the side surface, the reflected light energy at the scratch (or defect) 31 of the crystal blank 1 and at the edge processed portion increases. The direction of light emitted from the periphery of the crystal blank 1 is omnidirectional in the horizontal direction due to scattering. However, if there is no flaw in the crystal blank 1, the light path is not blocked, and the scattered light is transmitted light. I will pass. On the other hand, if there is an edge or a flaw 31, the light hits there and becomes reflected light 33 and is emphasized.

When the scattered light 32 hits the flaw 31, it is reflected and a flaw appears on the surface of the quartz blank 1. Since the light 31 is radiated from all directions to the flaw 31, the energy of the reflected light of the flaw 31 is emphasized, and when viewed from above the quartz blank 1, the flaw 31 appears to float clearly. Crystal flaws have all directions, so when irradiating light in one direction, flaws parallel to the light do not reflect and are difficult to detect.For example, when irradiating light in three directions, Even so, it is difficult to detect flaws with high accuracy due to poor SN ratio.
However, the S / N ratio can be remarkably improved by using the synergistic effect of light by intensively applying the diffused light to the flaws 31 from all sides and all directions as in the present embodiment, and reducing the flaws to small flaws. It is also possible to detect with high accuracy. In particular, scratches that are difficult to detect with human eyes (10-20 μm or less)
However, the detection becomes possible by increasing the light intensity relatively.

Further, since the image can be taken and image-processed with the whole crystal blank as a field of view at a time, even a small flaw (10 μm or less) can be detected at high speed. For example, even if the image is processed as a 512 × 512 image, it can be detected at a speed of 200 ms or less.
The same is true for any number of scratches in a single crystal blank.
Further, even a small flaw having a size of 10 to 20 μm or less has a large light energy and can be detected stably, which facilitates automation by image processing.

Further, if the edge processing accuracy of the peripheral surface of the quartz crystal blank is rough, the reflection of light at the edge portion becomes large, but if the accuracy is good, the reflection becomes small. Can also be applied to the inspection of the processing accuracy of a quartz blank. Further, if the reflection on the edge processed surface is used, it can be applied to the measurement of the shape and dimensions of the quartz blank.

The light irradiation angle on the surface of the quartz blank is preferably in the range of + 30 ° to -30 °. The reason for this range is that the S / N ratio is large and the flaw 31 can be clearly distinguished up to an irradiation angle of ± 30 °, but if it exceeds that, a large number of base patterns on the mounting table appear, making the determination difficult.
For example, if the angle is ± 45 °, the image of the scratch 31 is completely absorbed by the base pattern, and the scratch 31 cannot be detected.

The crystal blank 1 having undergone the flaw inspection is sucked again by the vacuum chuck 16 and transported by the transport robot arm 15 to the next step. At this time, since the groove is formed in the mounting surface 3 of the mounting table 2, the crystal blank 1 does not come into close contact with the mounting table 2 and does not come off.
Smooth pick-up and smooth transport are possible.

FIG. 2 is an image of a quartz blank actually observed. The background and quartz blank appear black because of the dark field, and the outlines and scratches of the blank appear white. Originally, it is ideal that no scratches exist over the entire surface. The outline is also preferably rectangular. However, in reality, it is impossible to obtain what is ideal, and as shown in the figure, corners are missing, scratches are in contact with some sides, or are inside. The scratch detection device,
Since such scratches and chips can be clearly identified in the image, it is possible to use them to uniformly eliminate them as defective products. However, some of them have scars that are not problematic in practical use. For example, there may be some scratches or chips depending on the location of the blank. To remedy these, when inspecting the crystal blank for scratches, divide the image of the blank surface of the crystal blank into a plurality of areas, set the inspection standards required for the areas for each area, and use the set inspection criteria. Each area needs to be inspected.

Therefore, in the present embodiment, as shown in FIG. 1, the image of the strip-shaped crystal blank 1 is divided into a plurality. D
The area is a corner area of the four corners of the blank, the area A is a pair of strip-shaped upper and lower areas parallel to the upper and lower sides of the blank excluding the corner area D, and the B area is the left and right sides of the blank excluding the corner area D. A pair of band-shaped left and right regions parallel to the side and having the left and right sides as one side, and a region C is a region A and a region A.
And a central area surrounded by areas B (peripheral areas) . The inspection standard is the most severe because the region C mainly functions as a quartz oscillator. Since the region A includes a long side, severe is required next. Since the area B includes the short side, the rank is lowered. Since the region D is a portion to be fixed with a brazing material (fixed region) , some scratches and chipping can be ignored.

Such an area designation is set from the personal computer 10 shown in FIG. A setting screen by the personal computer 10 for the inspection of the crystal blank for scratches will be described with reference to FIG.

First, a parameter button on the toolbar displayed on the setting screen is selected. When you select it, a screen as shown in the figure is displayed, but from the left half of the screen,
The parameter file name (test
1. PAR) is displayed. A read button, save button, and print button are provided.The user can click the read button to read the setting values, click the save button to save the setting values, and click the print button to print the setting contents. It has become.

In the shape selection box, there are prepared three round boxes of two strips and a round shape indicating a flaw inspection mode, and a bevel indicating a beveling inspection mode. Indicates that the shape of the crystal blank is a rectangular strip, and a mark in a round round box indicates that the crystal blank is a circular round shape. When a mark is put in the beveling round box, it means that the beveling mode for inspecting the beveling state is performed instead of the flaw inspection. In the illustrated example, a mark is put in a rectangular round box.

Boxes A and B are provided in the short side dimension column of the A and B areas. The short side length of the A area is set in the A box, and the short side length of the B area is set in mm in the B box. To be entered. In the illustrated example, 0.020 (mm) is stored in the A box and 0.100 (m) is stored in the B box.
m) is set.

The figure shown below the short side dimension column of the A and B areas is an explanatory view of the divided area of the strip-shaped quartz blank. An automatic parameter setting button is provided at the bottom,
Each parameter is automatically set by clicking a parameter automatic setting button.

Next, the right half of the screen will be described. A long side box, a short side box, a diagonal display, and an R (corner) box are provided in the external dimensions column. The long side box has a long side standard and allowable error size of the crystal blank, and the short side box has a short side. Standards and tolerances can be entered in mm units. The diagonal means the length of the diagonal of the quartz blank,
It is provided in order to eliminate blanks having a shape other than a rectangle, for example, a rhombus or asymmetrical left and right. The diagonal is displayed by automatic calculation when the long side and short side of the blank are input, and only the tolerance box can be input. The length of this diagonal is
It is a common standard that is inspected for a pair of diagonals. This item can be defined by an angle instead of a diagonal line. In the R (corner) box, a minimum distance standard and an allowable error dimension from an ideal right-angled corner area to an actual rounded corner area can be input in mm units.

The external dimensions are set as follows in the illustrated example.

Long side 6.000 ± 0.012 (mm) Short side 1.800 ± 0.020 (mm) Diagonal 1.800 ± 0.141 (mm) R (corner) 0.050 ± 0.030 (Mm) The shape of the crystal blank to be inspected is inspected according to the set values of the external dimensions, and if it is within the allowable value, it is a non-defective product, and if it exceeds the allowable value, it is a defective product.

The A (long side) level and A scratch area box, B (short side) level and B scratch area box, C (internal) level and C scratch area box, D
A (four corners) level and a D-scratch area box, a C (inside) stain and a C-stain area box are provided, and a set value can be input to each box. Here, the stain refers to dirt, an oil film, and the like that adhere to the surface of the crystal blank. Each level is
The threshold value (arbitrary unit) of the brightness of the image for binarizing the captured image is shown, and the area indicates the minimum area (arbitrary unit) that is determined as a flaw in each region. Therefore, when the image captured by the imaging device is at or above the set level and is at or above the set scratch area, it is determined to be a scratch only. If it is lower than the set level, it is not determined as a scratch. Various variances are represented by 256 gradations in 8 bits, and an A box, a B box, and a C box are provided, and a set value can be input to those boxes. The requirement of the dispersion setting value is further weighted under the AND condition of the level and the wound area under the AND condition.

Here, the above-mentioned judgment level and the wound area are set as follows.

A (long side) level 150 A scratch area 5 B (short side) level 150 B scratch area 5 C (internal) level 100 C scratch area 10 D (four corners) level 200 D scratch area 5 C (internal) stain 30 C spot area 40 Various dispersions A100 B150 C80 The unblemished part of the quartz blank appears dark, but the flawed part becomes bright. Therefore, the intended level of the setting level for each area is that the darkest (severe) threshold value is set in the C area where a strict standard is required, and the brightest (loose) threshold is set in the D area where the standard is the least strict. The value is set. Further, the area of the flaw in the region C is set to be somewhat larger than the other regions in relation to the set level. Further, regarding the stains in the region C, a significant difference from the scratches is set by setting the stain level small because the degree of light enhancement is lower than that of the scratches and by setting the stain area large since the spreads are larger than the scratches. Is attached. Further, regarding the dispersion, the standard in the C region is the strictest.

A flaw of the crystal blank to be inspected is selected based on the judgment level, the flaw area, and the variance. If the flaw is within the allowable value, it is not treated as a flaw. If the flaw exceeds the permissible value, it is treated as a flaw.

A parameter write button (F8) and an end button (F10) are provided side by side at the bottom of the right side. By clicking the parameter write button (F8), parameters can be written or the inspection setting can be ended. .

In the above embodiment, the quartz blank is divided into four types of A to D regions, but the present invention is not limited to this. For example, as shown in FIG. 7, (a) the central area C is further divided into a plurality or grids (C11, C12).
..) May be made to be able to examine the tendency of uneven distribution of flaws in the non-processed portion. When the crystal blank is round, the crystal blank is divided into a peripheral area A, a central area C, and an orientation flat area B as shown in FIG.
May be simply divided into the peripheral area A and the central area C, or the number of areas may be divided according to needs.

FIG. 6 shows a setting screen for beveling inspection of a crystal blank. The difference from FIG. 5 is that the dimensions of the areas A and B are set to be large in accordance with the beveling inspection, and the setting screens for the external dimensions and the flat part dimensions are slightly different. Note that the flat portion refers to a central non-processed portion excluding a peripheral portion to beveled, and thus the flat portion dimension refers to a dimension of the non-processed portion. In this way, even in the beveling inspection, the symmetry of the beveling processing accuracy required to improve the characteristics of the crystal unit is accurately measured by dividing the region and performing inspection using different set values for each region. become able to.

[0040]

According to the first aspect of the present invention, an appropriate inspection can be performed based on an inspection standard corresponding to an area. Claim 2
Invention According described, can proper inspection in accordance with the predetermined region, since the test data can be obtained that contains area information, that a easier to standardize and analytical control of the inspection.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing area division of a crystal blank image according to an embodiment.

FIG. 2 is an explanatory diagram showing an actual crystal blank image according to the embodiment.

3A and 3B show an embodiment of a quartz substrate beveling evaluation apparatus according to the present invention, wherein FIG. 3A is a schematic configuration diagram, and FIG.
FIG. 3A is a view of the light emitting diode and the mounting table of FIG.

FIG. 4 shows the principle that a flaw rises when light is irradiated toward the entire periphery of the side surface of the quartz blank, and (a)
Is a plan view, and (b) is a side view.

FIG. 5 is a view showing a setting screen of the personal computer at the time of a flaw inspection according to the embodiment.

FIG. 6 is a diagram showing a setting screen of a personal computer at the time of beveling evaluation according to the embodiment.

FIG. 7 is an explanatory diagram showing a region division of a quartz blank according to another embodiment.

[Explanation of symbols]

 1 Crystal blank A Upper and lower area B Left and right area C Central area D Corner area

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 21/84-21/90 G06T 7/00

Claims (2)

(57) [Claims] When inspecting a quartz crystal blank for a quartz oscillator for scratches , an image of the quartz crystal blank surface must be at least quartz crystal.
Fixed area for fixing the blank, crystal blank excluding the fixed area
Around the rank, the center that mainly functions as a crystal unit
The area is divided into a plurality of areas, an inspection standard required for the area is set for each area, and each area is inspected according to the set inspection standard.
Inspection method of crystal blank . 2. The crystal blank according to claim 1, wherein said crystal blank is a strip-shaped crystal blank.
There is, the corner regions der of the four corners of the fixed area is crystal blank
And the peripheral region is a quartz crystal blank excluding the corner region.
On a pair of strips parallel to the upper and lower sides of the
The quartz crystal block excluding the lower area and the corner area
A pair of strips parallel to the left and right sides of the rank, with the left and right sides as one side
The central area is surrounded by the upper and lower areas and the left and right areas.
2. The method for inspecting a quartz blank according to claim 1, wherein the blank is a central region .